/Engine/Plugins/Importers/USDImporter/Source/USDStageEditorViewModels/Public/USDObjectFieldViewModel.h
This member function is necessary because the no-RTTI slate module can't query USD for the available token options.
[TArray](API\Runtime\Core\Containers\TArray)< [TSharedPtr](API\Runtime\Core\Templates\TSharedPtr)< [FString](API\Runtime\Core\Containers\FString) > > GetDropdownOptions() const